Methods of forming semiconductor devices using semi-bidirectional patterning and islands

ABSTRACT

Devices and methods of fabricating integrated circuit devices using semi-bidirectional patterning are provided. One method includes, for instance: obtaining an intermediate semiconductor device having a dielectric layer, a first hardmask layer, a second hardmask layer, a third hardmask layer, and a lithography stack; patterning a first set of lines; patterning a second set of lines between the first set of lines; etching to define a combination of the first and second set of lines; depositing a second lithography stack; patterning a set of islands; etching to define the set of islands, leaving an OPL; depositing a spacer over the OPL; etching the spacer, leaving a vertical set of spacers; and etching the second hardmask layer using the third hardmask layer and the set of vertical spacers as masks.

FIELD OF THE INVENTION

The present invention relates to methods of fabricating semiconductordevices, and more particularly, to methods of using semi-bidirectionalpatterning with critical spacing control.

BACKGROUND OF THE INVENTION

For 64 nanometer (nm) and below pitch in nodes, especially in 7 nmnodes, self-aligned double patterning (SADP) of the nodes presentschallenges. For instance, power rails become a challenge due to theability to connect, for example, the metal 1, 2, and 3 areas requiremore directionality for metal orientation and end up like a “staple”rather than the traditional “rail.” The limited pattern variation doesnot allow for proper spacing and patterning of the nodes to control theend structure.

Therefore, it may be desirable to develop methods of fabricating nodeswith semi-bidirectional patterning.

BRIEF SUMMARY

The shortcomings of the prior art are overcome and additional advantageare provided through the provisions, in one aspect, a method thatincludes, for instance: obtaining an intermediate semiconductor devicehaving a dielectric layer, a first hardmask layer, a second hardmasklayer, a third hardmask layer, and a lithography stack; patterning afirst set of lines in a first direction; patterning a second set oflines in the first direction between the first set of lines; etching thelithography stack to define a combination of the first and second set oflines in the third hardmask layer; depositing a second lithography stackover the second hardmask layer and the third hardmask layer; patterninga set of islands; etching the second lithography stack defining the setof islands in the third hardmask layer, leaving an optical planarizationlayer (OPL) above the third hardmask layer where the set of islands wasnot etched; depositing a spacer over the OPL and over the secondhardmask layer in the set of islands; etching the spacer, leaving a setof vertical spacers lining the set of islands; removing the OPL; andetching the second hardmask layer using the third hardmask layer and theset of vertical spacers as masks.

In another aspect, an intermediate semiconductor device is providedwhich includes, for instance: a dielectric layer, a first hardmasklayer, a set of nitride lines periodically in a first directionapproximately 15 nm to approximately 35 nm wide, and a set of connectingnitride lines in a second direction, wherein a width of the set ofconnecting nitride lines is less than a width of the set of nitridelines.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

One or more aspects of the present invention are particularly pointedout and distinctly claimed as examples in the claims at the conclusionof the specification. The foregoing and other objects, features, andadvantages of the invention are apparent from the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 depicts one embodiment of a method for forming an intermediatesemiconductor interconnect structure, in accordance with one or moreaspects of the present invention;

FIG. 2A depicts a top down view of one embodiment of an intermediatesemiconductor interconnect structure having a dielectric layer, a firsthardmask layer, a second hardmask layer, a third hardmask layer, and alithography stack with a first set of lines patterned, in accordancewith one or more aspects of the present invention;

FIG. 2B depicts a cross-sectional elevation isometric three-dimensionalview of the structure of FIG. 2A, in accordance with one or more aspectsof the present invention;

FIG. 3A depicts the structure of FIG. 2A after patterning a second setof lines, in accordance with one or more aspects of the presentinvention;

FIG. 3B depicts a cross-sectional elevation isometric three-dimensionalview of the structure of FIG. 3A, in accordance with one or more aspectsof the present invention;

FIG. 4A depicts the structure of FIG. 3A after etching the lithographystack to define a combination of the first and second set of lines inthe third hardmask layer, in accordance with one or more aspects of thepresent invention;

FIG. 4B depicts a cross-sectional elevation isometric three-dimensionalview of the structure of FIG. 4A, in accordance with one or more aspectsof the present invention;

FIG. 5A depicts the structure of FIG. 4A after depositing a secondlithography stack and patterning a set of islands, in accordance withone or more aspects of the present invention;

FIG. 5B depicts a cross-sectional elevation isometric three-dimensionalview of the structure of FIG. 5A, in accordance with one or more aspectsof the present invention;

FIG. 6A depicts the structure of FIG. 5A after etching the secondlithography stack to define the set of islands in the third hardmasklayer, leaving an OPL above the third hardmask layer where the set ofislands was not etched, in accordance with one or more aspects of thepresent invention;

FIG. 6B depicts a cross-sectional elevation isometric three-dimensionalview of the structure of FIG. 6A, in accordance with one or more aspectsof the present invention;

FIG. 7A depicts the structure of FIG. 6A after depositing a spacer overthe OPL and the second hardmask layer in the set of islands and etchingthe spacer, leaving a vertical set of spacers, in accordance with one ormore aspects of the present invention;

FIG. 7B depicts a cross-sectional elevation isometric three-dimensionalview of the structure of FIG. 7A, in accordance with one or more aspectsof the present invention;

FIG. 7C depicts the structure of FIG. 7B after etching the spacer, inaccordance with one or more aspects of the present invention;

FIG. 8A depicts the structure of FIG. 7C after removing the OPL, inaccordance with one or more aspects of the present invention;

FIG. 8B depicts a cross-sectional elevation isometric three-dimensionalview of the structure of FIG. 8A, in accordance with one or more aspectsof the present invention;

FIG. 9A depicts the structure of FIG. 8A after etching the secondhardmask layer using the third hardmask layer and the set of verticalspacers as a mask, in accordance with one or more aspects of the presentinvention;

FIG. 9B depicts a cross-sectional elevation isometric three-dimensionalview of the structure of FIG. 9A, in accordance with one or more aspectsof the present invention;

FIG. 10 depicts a top down view of one embodiment of an intermediatesemiconductor interconnect structure for an alternative cell oriented ina different direction and having a dielectric layer, a first hardmasklayer, a second hardmask layer, a third hardmask layer, and alithography stack with a first set of lines patterned, in accordancewith one or more aspects of the present invention;

FIG. 11 depicts the structure of FIG. 10 after patterning a second setof lines, in accordance with one or more aspects of the presentinvention;

FIG. 12 depicts the structure of FIG. 11 after etching the lithographystack to define a combination of the first and second set of lines inthe third hardmask layer, in accordance with one or more aspects of thepresent invention;

FIG. 13 depicts the structure of FIG. 12 after depositing a secondlithography stack and patterning a block shaped set of islands, inaccordance with one or more aspects of the present invention;

FIG. 14 depicts the structure of FIG. 13 after etching the secondlithography stack to define the set of islands in the third hardmasklayer, leaving an OPL above the third hardmask layer where the set ofislands was not etched, in accordance with one or more aspects of thepresent invention;

FIG. 15 depicts the structure of FIG. 14 after depositing a spacer overthe OPL and the second hardmask layer in the set of islands and etchingthe spacer, leaving a vertical set of spacers, in accordance with one ormore aspects of the present invention;

FIG. 16 depicts the structure of FIG. 15 after removing the OPL, inaccordance with one or more aspects of the present invention; and

FIG. 17 depicts the structure of FIG. 16 after etching the secondhardmask layer using the third hardmask layer and the set of verticalspacers as a mask, in accordance with one or more aspects of the presentinvention.

DETAILED DESCRIPTION

Aspects of the present invention and certain features, advantages, anddetails thereof, are explained more fully below with reference to thenon-limiting embodiments illustrated in the accompanying drawings.Descriptions of well-known materials, fabrication tools, processingtechniques, etc., are omitted so as to not unnecessarily obscure theinvention in detail. It should be understood, however, that the detaileddescription and the specific examples, while indicating embodiments ofthe invention, are given by way of illustration only, and are not by wayof limitation. Various substitutions, modifications, additions and/orarrangements within the spirit and/or scope of the underlying inventiveconcepts will be apparent to those skilled in the art from thisdisclosure. Note also that reference is made below to the drawings,which are not drawn to scale for ease of understanding, wherein the samereference numbers used throughout different figures designate the sameor similar components.

Generally stated, disclosed herein are certain integrated circuits,which provide advantages over the above noted, existing semiconductordevices and fabrication processes. Advantageously, the integratedcircuit device fabrication processes disclosed herein provide for uniquestructures utilizing a semi-bidirectional patterning method.

In one aspect, in one embodiment, as shown in FIG. 1, an integratedcircuit device formation process in accordance with one or more aspectsof the present invention may include, for instance: obtaining anintermediate semiconductor interconnect device having a dielectriclayer, a first hardmask layer, a second hardmask layer, a third hardmasklayer, and a lithography stack 100; patterning a first set of lines in afirst direction 105; patterning a second set of lines in the firstdirection between the first set of lines 110; etching the lithographystack to define a combination of the first and second set of lines inthe third hardmask layer 115; depositing a second lithography stack overthe second hardmask layer and the third hardmask layer 120; patterning athird set of lines in a second direction perpendicular to the first andsecond set of lines 125; etching the second lithography stack definingthe third set of lines in the third hardmask layer, leaving an OPL abovethe third hardmask layer where the third set of lines was not etched130; depositing a spacer over the OPL and over the second hardmask layerin the third set of lines 135; etching the spacer, leaving a set ofvertical spacers lining the third set of lines 140; removing the OPL145, and etching the second hardmask layer using the third hardmasklayer and the set of vertical spacers as masks 150.

FIGS. 2-9 depict, by way of example only, one detailed embodiment of aportion of a semiconductor device formation process and a portion of anintermediate semiconductor structure, in accordance with one or moreaspects of the present invention. Note that these figures are not drawnto scale in order to facilitate understanding of the invention, and thatthe same reference numerals used throughout different figures designatethe same or similar elements.

FIG. 2A shows a portion of an intermediate semiconductor devicegenerally denoted 200, depicted at an intermediate semiconductorfabrication stage. In these embodiments and as illustrated, device 200may be a logic device, including but not limited to a 6T logic device ora 7.5T logic device. The device 200 may have been processed throughinitial device processing steps in accordance with the design of thedevice 200 being fabricated. For example, the device 200 may include,for instance, a dielectric layer 205, which may include any materialwith a smaller dielectric constant (k) than silicon dioxide. This layercan act as a substrate, or may be deposited on a substrate (not shown).Dielectric layer 205 can include any dielectric materials, including butnot limited to any inorganic dielectric materials, organic dielectricmaterials, or combinations thereof. Suitable dielectric materials caninclude carbon-doped silicon dioxide materials; fluorinated silicateglass (FSG); organic polymeric thermoset materials; silicon oxycarbide;SiCOH dielectrics; fluorine doped silicon oxide; spin-on glasses;silsesquioxanes, including hydrogen silsesquioxane (HSQ), methylsilsesquioxane (MSQ) and mixtures or copolymers of HSQ and MSQ;benzocyclobutene (BCB)-based polymer dielectrics, and anysilicon-containing low-k dielectric. Examples of spin-on low-k filmswith SiCOH-type composition using silsesquioxane chemistry include HOSP™(available from Honeywell), JSR 5109 and 5108 (available from JapanSynthetic Rubber), Zirkon™ (available from Shipley Microelectronics, adivision of Rohm and Haas), and porous low-k (ELk) materials (availablefrom Applied Materials). Examples of carbon-doped silicon dioxidematerials, or organosilanes, include Black Diamond™ (available fromApplied Materials) and Coral™ (available from Novellus). An example ofan HSQ material is FOx™ (available from Dow Corning). In someembodiments, dielectric materials include organic polymeric thermosetmaterials, consisting essentially of carbon, oxygen, and hydrogen.Additionally, dielectric materials may include the low-k polyaryleneether polymeric material known as SiLK™ (available from The Dow ChemicalCompany), and the low-k polymeric material known as FLARE™ (availablefrom Honeywell).

In another embodiment (not shown), the substrate of device 200 may be,for example, a silicon on insulator (SOI) substrate (not shown). Forexample, the SOI substrate may include an isolation layer (not shown),which may be a local buried oxide region (BOX) or any suitable materialfor electrically isolating transistors, aligned with the gate structure.In some embodiments, the device is a portion of a back end of line(BEOL) portion of an integrated circuit (IC).

Still referring to FIG. 2A, above the dielectric layer 205 may be afirst hardmask layer 210, such as SacSiN, SiN, SiO₂, SiON, or othermasking materials, which may be exposed in the final device 200. Abovethis can be a second hardmask layer 215, for instance SiN, SiO₂, SiON,or a nitride material such as titanium nitride (TiN), which is typicallydifferent from the first hardmask layer 210. Above this may be a thirdhardmask layer 220, which may consist of any of the above describedhardmask materials. While three hardmask layers are described, anynumber of hardmask layers may be used. Above the hardmask layers 210,215, and 220, is a lithography stack 225. The lithography stack 225 caninclude multiple layers and can vary depending on the type oflithography used for patterning and etching device 200. For instance,lithography stack 225 may include an optical planarization layer (OPL)230, a SiON layer 235, a bottom antireflective coating (BARC) layer 240,and a photoresist layer 245. These materials may vary, and thedisclosure should be understood to include any variation and combinationof layers useful in lithography and etching techniques relevant to theart.

As depicted in FIG. 2B, a first set of lines 250 may be patterned in afirst direction. As can be seen in FIG. 2B, patterning may includeexposing the photoresist layer 245 to a light that will remove thephotoresist layer 245 in the shape of the first set of lines 250.

As depicted in FIG. 3A, in order to create smaller lines, for instancein an interconnect device, a second set of lines 255 may be patterned,either in the same lithography stack 225 or in a new lithography stack325, as shown in FIG. 3B. The second set of lines 255 may be patternedin the same first direction of the first set of lines 250, and may bebetween the first set of lines 250 to narrow spaces between the two setsof lines. As depicted in FIG. 3B, the first set of lines are etched intothe third hardmask layer 220 before adding the new lithography stack325, which can include the same layers and materials as the firstlithography stack 225.

As depicted in FIG. 4A, the lithography stack 225 and/or 325 may both bepatterned creating a pattern of the combination of lines. As depicted inFIG. 4B, the combined pattern may be etched, removing the lithographystacks, in order to define a combination of the first set of lines 250and the second set of lines 255 into the third hardmask layer 220. Forinstance, when the second set of lines 255 is between the first set oflines 250, each adjacent line may be approximately 26 nm apart from oneanother once etched in combination. The process described andillustrated in FIGS. 2-4 are sometimes referred to as LELE, orlithography-etch/lithography-etch due to the patterning and etching oftwo distinct sets of lines 250 and 255. In embodiments where device 200is a logic device, the first and second set of lines 250/255 may beapproximately 30 nm wide.

As depicted in FIG. 5A, following the etching of the combination of thefirst two sets of lines, a set of islands 260 may be patterned in asecond direction, for instance perpendicular to the direction of thefirst two sets of lines 250/255. In some embodiments, the set of linesmay include line segments, approximately equal in width to the first andsecond set of lines 250 and 255, but only long enough to connect two ofthe lines from the first set of lines 250 and 255. Thus, the length ofislands 260, as seen in FIG. 5A, shows the underlying lines connected bythe set of islands 260. As depicted in FIG. 5B, in order to pattern theset of islands 260, a second lithography stack 525 may be deposited overthe second hardmask layer 215, which is defined and exposed by theetching of the first and second set of lines 250/255, and over the thirdhardmask layer 220, which is now defined by the space between the firsttwo sets of lines 250 and 255. As can be seen in FIG. 5B, these linesrun perpendicular to the previous lines, and are patterned in a similarphotoresist layer 245 of a lithography stack 525 (FIG. 5A) as the firsttwo sets of lines.

As depicted in FIG. 6A, the set of islands 260 are provided in thesecond direction. FIG. 6B depicts that the second lithography stack 525may be etched, defining the set of islands 260 in the underlying thirdhardmask layer 220, essentially causing a partial grid pattern incombination with the first and second set of lines 250/255, but leavingan OPL 630, usually left behind after etching second lithography stack525, but it may be added after etching. In any event, OPL 630 shouldonly be above the areas not etched in etching the set of islands 260. Inembodiments where device 200 is a logic device, each island of the setof islands 260 may be approximately 164 nm apart for a 6T logic device,or approximately 226 nm apart for a 7.5T logic device. The third set oflines 260 may be approximately 76 nm wide. These widths are approximateand can include +/−5 nm. It should also be understood that these valuesare for a particular logic device, but can vary depending on the logicdevice desired.

As depicted in FIGS. 7A and 7B, a spacer 265 is deposited over the OPL630 where it exists, and over the second hardmask layer 215 in the setof islands 260. As can be seen in FIG. 7B, the spacer 265 forms on a topsurface of the OPL 630 and lines the walls of and bottom of the set ofislands 260. The spacer 265 can include an oxide mask, for instanceSiO₂. It may be deposited, for example, by atomic layer deposition (ALD)in order to form an even layer over all surfaces. FIG. 7C depict device200 following etching of the spacer 265, wherein a set of verticalspacers 270 are formed by etching the spacer, effectively removing anyhorizontal portions of spacer 265, both the portions over the OPL 630and the second hardmask layer 215 at the bottom of third set of lines260. The processes illustrated in FIGS. 6-7 may be considered aself-aligned patterning (SAP) due to the use of spacers in the etchedset of islands 260. Thus, in some embodiments, aspects of the currentdisclosure include a novel combination of LELE techniques and SAPtechniques to form a new structure.

As depicted in FIG. 8A, the OPL 630 may be removed, leaving behind thecombined pattern of the parallel first and second set of lines 250/255,broken by the perpendicular set of islands 260 and, parallel to set ofislands 260, the set of vertical spacers 270. FIG. 8B shows athree-dimensional view of the set of vertical spacer 270.

As depicted in FIGS. 9A and 9B, the third hardmask layer remainingbetween all sets of lines and islands and the set of vertical spacers270 act as a mask for etching the underlying second hardmask layer 215to form the partial grid pattern illustrated. As such, a device 200 isillustrated in FIGS. 9A and 9B which includes the dielectric layer 205,the first hardmask layer 210, which is partially exposed by areas notcovered by the remaining second hardmask layer 215. For instance, theremaining second hardmask layer 215 has been etched to form a set ofnitride lines 950 periodically, left behind by the first and second setof lines 250/255, FIGS. 2A and 3A. Also formed is a set of connectingnitride lines 960 from the third set of lines 260, FIG. 5A. Asillustrated in FIGS. 9A and 9B, the spacing between the lines can beuniformly patterned according to some embodiments. For instance, the setof nitride lines 950 are approximately 15 nm to approximately 35 nmwide, in some embodiments 26 nm wide. This width is determined by thelithography steps described above. The set of connecting lines areapproximately 10 nm to approximately 30 nm wide, in some embodimentsapproximately 20 nm wide, which is defined by the spacer thickness, andoriented in a perpendicular direction, and typically smaller than thewidth of the first set of lines due to the process differences. Inembodiments where device 200 includes a logic device, the nitride linesmay be approximately 30 nm apart, typically uniformly. The connectinglines 960, which are typically grouped into sets of two adjacent lines,which can be approximately 36 nm apart from any adjacent line. The linesmake up the bit lines of a cell of a logic device, an SRAM cell, orother devices that benefit from the illustrated orientation. These linesare patterned in order to increase the efficiency of the M1 transistorof a cell, and thus can be patterned at spacing necessary to operate thedesired logic device cell or the SRAM cell. For instance, followingformation of the nitride lines, the resulting pattern is used to form acell using known BEOL processing techniques. For instance, using thepattern as a hardmask, the structure is etched again and the trench andvias are filled with a metal, such as copper, and polished to achievethe structure of the end cell.

It is to be understood that the pattern illustrated in FIG. 9 can beuseful, for instance, in a logic device 200, but may be patterneddifferently and with different spacing depending on the desiredstructure and function. For instance, a similar method can be used forembodiments involving SRAM cells, as will be described below.

FIGS. 10-17 depict, by way of example only, one alternative embodimentof a portion of a semiconductor device formation process and a portionof an intermediate semiconductor structure, in accordance with one ormore aspects of the present invention. Note that these figures are notdrawn to scale in order to facilitate understanding of the invention,and that the same reference numerals used throughout different figuresdesignate the same or similar elements.

FIG. 10 shows a portion of an intermediate semiconductor devicegenerally denoted 200, depicted at an intermediate semiconductorfabrication stage. In these embodiments and as illustrated, device 200may be an SRAM cell or similar device. The device 200 may have beenprocessed through initial device processing steps in accordance with thedesign of the device 200 being fabricated. In FIGS. 11-18, only the topdown view is shown, as depicting the stacks cutaway are substantiallysimilar to the embodiments illustrated in FIGS. 2-10. Therefore, thereference numerals below refer to the same materials. For example, thedevice 200 may include, for instance, a dielectric layer 205, which mayinclude any material with a smaller dielectric constant (k) than silicondioxide. This layer can act as a substrate, or may be deposited on asubstrate (not shown).

In another embodiment (not shown), the substrate of device 200 may be,for example, a silicon on insulator (SOI) substrate (not shown). Forexample, the SOI substrate may include an isolation layer (not shown),which may be a local buried oxide region (BOX) or any suitable materialfor electrically isolating transistors, aligned with the gate structure.In some embodiments, the device is a portion of a back end of line(BEOL) portion of an integrated circuit (IC).

Still referring to FIG. 10, above a dielectric layer 205 may be a firsthardmask layer 210, which may be exposed in the final device 200. Abovethis can be a second hardmask layer 215, for instance titanium nitride(TiN), a third hardmask layer 220, and a lithography stack 225. Thelithography stack 225 can include multiple layers and can vary dependingon the type of lithography used for patterning and etching device 200.For instance, lithography stack 225 may include an OPL 230, a SiON layer235, a BARC layer 240, and a photoresist layer 245. These materials mayvary, and the disclosure should be understood to include any variationand combination of layers useful in lithography and etching techniquesrelevant to the art.

As depicted in FIG. 10, a first set of lines 250 may be patterned in afirst direction. The patterning may include exposing the photoresistlayer 245 to a light that will remove the photoresist layer 245 in theshape of the first set of lines 250.

As depicted in FIG. 11, in order to create smaller lines, for instancein an interconnect device, a second set of lines 255 may be patterned,either in the same lithography stack 225 or in a new lithography stack325. The second set of lines 255 may be patterned in the same firstdirection of the first set of lines 250, and may be between the firstset of lines 250 to narrow spaces between the two sets of lines.

As depicted in FIG. 12, the lithography stack 225 and/or 325 may beetched away to define a combination of the first set of line 250 and thesecond set of lines 255. For instance, when the second set of lines 255is between the first set of lines 250, each adjacent line may beapproximately 26 nm apart from one another once etched in combination.The process described and illustrated in FIGS. 10-12 are sometimesreferred to as LELE, or lithography-etch/lithography-etch due to thepatterning and etching of two distinct sets of lines 250 and 255. Inembodiments where device 200 is a SRAM cell, the first and second set oflines 250/255 may be approximately 64 nm wide, and typically areoriented perpendicular to those of a logic device as depicted in FIGS.2-10.

As depicted in FIG. 13, following the etching of the combination of thefirst two sets of lines, a second lithography stack 525 may be depositedover the second hardmask layer 215, which is defined and exposed by theetching of the first and second set of lines 250/255, and over the thirdhardmask layer 220, which is now defined by the space between the firsttwo sets of lines. A set of islands 260 may be patterned, for instance,as a set of islands 260 that may include block shaped islands which canconnect portions of the first two sets of lines 250/255. As can be seenin FIG. 13, these islands can be block shaped, however any shape ofislands connecting any number of lines can be patterned. The linesegments above and the block shaped islands of these embodiments are notmeant to be limiting, but are merely examples of some of the shapespossible.

As depicted in FIG. 14, a second lithography stack 525 may be etched,defining the set of islands 260 in the underlying third hardmask layer220, essentially causing a block and line pattern in combination withthe first and second set of lines 250/255 (not shown below the layers inthe top down view), but leaving an OPL 630, usually left behind afteretching second lithography stack 525, but it may be added after etching.In any event, OPL 630 should only be above the areas not etched inetching the set of islands 260. In embodiments where device 200 is aSRAM cell, each island of the set of islands 260 may be approximately 36nm apart. The set of islands 260 may be approximately 76 nm wide. Thesewidths are approximate and can include +/−5 nm. It should also beunderstood that these values are for a particular SRAM cell, but canvary depending on the logic device desired.

As depicted in FIG. 15, a spacer layer 265 (not shown) is deposited overthe OPL 630 where it exists, and over the second hardmask layer 215 inthe set of islands 260 and etched away to form vertical spacers 270lining the outer edges of islands 960. The processes illustrated inFIGS. 14-15 may be considered a self-aligned patterning (SAP) due to theuse of spacers in the etched third set of lines 260. Thus, in someembodiments, aspects of the current disclosure include a novelcombination of LELE techniques and SAP techniques to form a newstructure.

As depicted in FIG. 16, the OPL 630 may be removed, leaving behind thecombined pattern of the parallel first and second set of lines 250/255,broken by the set of islands 260 and, surrounding the inner edges of setof islands 260, the set of vertical spacers 270.

As depicted in FIG. 17, the third hardmask layer remaining between allsets of lines and the set of vertical spacers 270 act as a mask foretching the underlying second hardmask layer 215 to form the partialgrid pattern illustrated. As such, a device 200 is illustrated in FIG.17, which includes the dielectric layer 205, the first hardmask layer210, which is partially exposed by areas not covered by the remainingsecond hardmask layer 215. For instance, the remaining second hardmasklayer 215 has been etched to form a set of nitride lines 950periodically, left behind by the first and second set of lines 250/255,FIGS. 10 and 11. Also formed is a set of connecting nitride lines 960from the set of islands 260, FIG. 13. In some embodiments, the set ofnitride lines 950 are approximately 26 nm wide due to the earlierpatterning, and the set of connecting nitride lines are approximately 20nm wide. In embodiments where device 200 includes a SRAM cell, thenitride lines may be approximately 64 nm apart, typically uniformly. Theconnecting nitride lines 960 can be approximately 36 nm apart from anyadjacent lines left from the islands. It is to be understood that thepattern illustrated in FIG. 17 can be useful, for instance, in an SRAMcell 200, but may be patterned differently and with different spacingdepending on the desired structure and function.

Thus, using embodiments described above, combining LELE and SAP methodsin a semi-bidirectional patterning technique allows for more controlledpatterning. This can alleviate power issues from the prior methods andallow for better connections between the portions of device 200 ordevice 1800, or a combination of the methods of the two embodiments.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprise” (andany form of comprise, such as “comprises” and “comprising”), “have” (andany form of have, such as “has” and “having”), “include” (and any formof include, such as “includes” and “including”), and “contain” (and anyform contain, such as “contains” and “containing”) are open-endedlinking verbs. As a result, a method or device that “comprises”, “has”,“includes” or “contains” one or more steps or elements possesses thoseone or more steps or elements, but is not limited to possessing onlythose one or more steps or elements. Likewise, a step of a method or anelement of a device that “comprises”, “has”, “includes” or “contains”one or more features possesses those one or more features, but is notlimited to possessing only those one or more features. Furthermore, adevice or structure that is configured in a certain way is configured inat least that way, but may also be configured in ways that are notlisted.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below, if any, areintended to include any structure, material, or act for performing thefunction in combination with other claimed elements as specificallyclaimed. The description of the present invention has been presented forpurposes of illustration and description, but is not intended to beexhaustive or limited to the invention in the form disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the invention.The embodiment was chosen and described in order to best explain theprinciples of one or more aspects of the invention and the practicalapplication, and to enable others of ordinary skill in the art tounderstand one or more aspects of the invention for various embodimentswith various modifications as are suited to the particular usecontemplated.

What is claimed is:
 1. A method comprising: obtaining an intermediatesemiconductor device having a dielectric layer, a first hardmask layer,a second hardmask layer, a third hardmask layer, and a lithographystack; patterning a first set of lines in a first direction; patterninga second set of lines in the first direction between the first set oflines; etching the lithography stack to define a combination of thefirst and second set of lines in the third hardmask layer; depositing asecond lithography stack over the second hardmask layer and the thirdhardmask layer; patterning a set of islands; etching the secondlithography stack defining the set of islands in the third hardmasklayer, leaving an OPL above the third hardmask layer where the set ofislands was not etched; depositing a spacer over the OPL and over thesecond hardmask layer in the set of islands; etching the spacer, leavinga set of vertical spacers lining the set of islands; removing the OPL;and etching the second hardmask layer using the third hardmask layer andthe set of vertical spacers as masks.
 2. The method of claim 1, whereineach adjacent line of the first and second lines are approximately 26 nmapart.
 3. The method of claim 2, wherein the set of islands comprise aset of line segments in a second direction perpendicular to the firstand second set of lines.
 4. The method of claim 3, wherein the first andthe second set of lines are approximately 30 nm wide.
 5. The method ofclaim 4, wherein each adjacent line segment of the set of islandsconnects two adjacent lines of the first and second set of lines.
 6. Themethod of claim 5, wherein the spacer over the OPL and the secondhardmask layer fills the set of islands.
 7. The method of claim 2,wherein the set of islands comprises a set of block shaped etches. 8.The method of claim 7, wherein the first and second set of lines areapproximately 30 nm wide, and the set of islands are approximately 38 nmapart in a first direction and approximately 73 nm apart in a seconddirection.
 9. The method of claim 8, wherein the spacer deposited overthe OPL, after etching, lines the set of islands, making the set ofislands without the spacer approximately 22 nm wide and 55 nm long. 10.The method of claim 9, wherein the set of islands, following etching ofthe second hardmask layer, define a grid shaped pattern connecting everyother adjacent set of the first and second lines.
 11. The method ofclaim 1, wherein the spacer comprises an oxide mask.
 12. The method ofclaim 11, wherein the oxide mask comprises SiO₂.
 13. The method of claim12, wherein the deposition comprises atomic layer deposition.
 14. Themethod of claim 1, wherein the second hardmask layer comprises TiN.